Linear polyester plasticizers



Patented July 28, 1953 UNITED STATES PATENT OFFICE to The Firestone Tire & Rubber Company, Akron, Ohio, a corporation of Ohio No Drawing; Application November 8, 195

Serial No. 255,540

15 Claims. (Cl. 260 3L4) n This invention relates to certain subresinous linear polyester plasticizers for vinyl chloride resins, and more particularly to the improveinent of the heat-ageing behavior of these plasticizers when compounded with the resins.

It has been discovered by associates of the present applicants that certain subresinous linear polyesters of (A) an alkylene dicarboxylic acid with (B) a glycol and (C) a monohydric alcohol provide excellent plasticizers for vinyl chloride resins. Hereinafter these materials will be referred to as linear polyesters. These linear polyesters have excellent efficiency as plasticizers, are not susceptible to excessive migration, and impart excellent low temperature properties to the resins in which they are incorporated. Such linear polyesters may be prepared in one of two Ways-( 1) by transesterification of an ester of the dicarboxylic acid with the glycol, or (2) by direct esterification of the free acid with the glycol and alcohol. Method ('2) is by far the less expensive; unfortunately vinyl chloride resins containing polyesters produced by method (2) exhibit relatively poorer heat ageing than resins containing the polyesters produced by method The above and other objects are secured, in accordance with this invention, by contacting with calcium oxide, at temperatures in the range 125-250" 0., for at least 15 minutes, a subresinous linear polyester produced by the direct esterification of a dicarboxylic acid With a glycol and with a monohydric alcohol. Linear polyesters so treated provide excellent plasticizing action in vinyl chloride resins into which they are incorporated, and likewise the compounded resins exhibit greatly enhanced resistance to heat ageing as compared with resins com ounded with linear polyesters not treated by the process or this invention.

THE sUBREsINoUs LINEAR POLYESTERS bon atoms 2 v The molecular proportions in the above schedule may be varied by about 10.1 mole in each case. If the reaction led to a single molecular species. that species would have the formula:

wherein Alo -O represents a monohydric alcohol residue CQ-A'c-CO--- represents a dioar'boxylic acid residue and o- G represents a glycol residue.

Table I Succinic acid Suberic acid Glutaric acid Undecanedicarboxylic Adipic acid acid Pimaric acid Dodecanedicarboxylic $ebacic acid acid Azelaic acid The gl'yoois and diglyools which may be employed may be any such com ounds containing from 2 to 12 carbon atoms, for example:

Table II 2,2-dihydroxy dipropyl ether 1,5-pentanediol 1,10-decanediol Z-ethyl pentanediol-l,3

Butanediol-1,3

Z-ethyl hexanediol-1,3

Table III The esterification of the acid, glycol and alcohol may be eifected under any usual esterin-Butanol 2-ethyl hexanol 2-butoxy ethanol n-Hexanol 3-ethyl hexanol fication conditions, typically by refluxing in a water-entraining solvent such as toluene. The water evolved is mechanically separated from the refluxing toluene before the latter is returned to the reaction mass. When water ceases to be evolved at an appreciable rate, the reaction mass is heated under reduced pressure to remove the solvent and remaining water and to drive the reaction further to completion.

THE TREATMENT WITH CALCIUM OXIDE The linear polyesters prepared as described above, even without the treatment of this invention, serve excellently in most respects as plasticizers in vinyl chloride resins, having good efficiency (i. e. plasticizing efiect per unit quantity of plasticizer employed) and freedom from spew, and imparting particularly good low temperature flexibility to vinyl chloride resins. Likewise the compositions containing these polyesters have excellent light stability. They have, however, the drawback that the resin compounds containingthem stiffen and darken upon prolonged exposure to heat, as in milling, extrusion, calendering, molding etc. After heating in contact with calcium oxide in accordance with this invention, however, the linear polyesters no longer have this disadvantage. In general, the heating should be carried out at a temperature of at least 150 C., and preferably at least 175 C., the maximum temperature being that at which the ester decomposes, say 250 C. A time of heatin of at least 15 minutes, preferably at least 30 minutes, should be employed, the maximum time being solely a matter of economy of equipment, as there does not seem to be any technical reason why heating should not be continued indefinitely. No substantial improvement will be noted beyond 3 hours heating. The amount of calcium oxide present is of minor importance; generally /2%, based on the weight of linear polyester being treated, will be operative to efiect a substantial improvement of the ester. Greater quantities, on the order of 2% or 3%, will generally be preferable. Since the calcium oxide constitutes a separate phase there would be no theoretical upper limit to the quantity used. As a practical matter, entrapment and loss of the polyester in the calcium oxide at the conclusion of the treatment begins to be uneconomicvwhen quantities as great as 10% are used. The calcium oxide should, of course, be in finely divided or pulverulent form to facilitate access of the polyester to the calcium oxide. The mass undergoing treatment may be agitated to ensure circulation and contact of the linear polyester and calcium oxide. The calcium oxide is separated from the polyester at the conclusion of the treatment by filtration, decantation. centrifugation or like mechanical means.

The linear polyesters are generally incorporated in the vinyl chloride resins to the extent of from about 10% to 60%, based on the weight of the resins.

'I'HE VINYL CHLORIDE RESINS The vinyl chloride resins which may be plasticized by the linear polyesters treated in accordance with this invention are a well-known class of materials consisting of simple polymers of vinyl chloride, and copolymers of vinyl chloride in which the essential polyvinyl chloride polymer chains are interspersed at intervals with the residues of other monoethylenically unsaturated compounds or conjugated diethylenically unsaturated compounds. In general, any resin having a substantial proportion of the polyvinyl chloride chain structure, so as to be susceptible to heat degradation by mechanisms involving the polyvinyl chloride chain, will be benefited by the addition of the stabilized polyesters treated in accordance with this invention. This will include a y vinyl chloride copolymers containing not more than 40%, based on the total weight of the resins, of these extraneous unsaturated compounds.

Conversely stated, the resins must contain at least 60% of vinyl chloride copolymerized therein. Suitable compounds for copolymerization with vinyl chloride include, for instance, vinyl esters on the order of vinyl bromide, vinyl fluoride, vinyl acetate, vinyl chloroacetate, vinyl butyrate, other fatty acid vinyl esters, vinyl alkyl sulfonates and the like; vinyl ethers such as vinyl ethyl ether, vinyl isopropyl ether, vinyl chloroethyl ether and the like; cyclic unsaturated compounds such as styrene, the monoand polychlorostyrenes, coumarone, indene, vinyl naphthalenes, vinyl pyridines, vinyl pyrrole and the like; acrylic acid and its derivatives such as ethyl acrylate, methyl methacrylate, ethyl methacrylate, ethyl chloroacrylate, acrylonitrile, methacrylonitrile, diethyl maleate, diethyl fumarate, and the like; vinylidene compounds on the order of vinylidene chloride, vinylidene bromide, vinylidene fluorochloride, and the like; unsaturated hydrocarbons such as ethylene, propylene, isobutene and the like; allyl compounds such as allyl acetate, allyl chloride, allyl ethyl ether and the like; and conjugated and cross-conjugated ethylenically unsaturated compounds such as butadiene, isoprene, chloroprene, 2,3-dimethylbutadiene-l,3, piperylene, divinyl ketone and the like. For a fairly complete list of materials known to copolymerize with vinyl chloride, reference may be had to Krczil, Kurzes Handbuch der Polymerisations- Technik-II, Mehrstoff Polymerization, Edwards Bros. Inc., 1945, pp. 735-747, the items under Vinyl chlorid. As a rough rule, the criterion of a practical comonomer for use with vinyl chloride to produce copolymers containing 60% or more of vinyl chloride is that, on a mole percentage basis, an initial charge of 96% vinyl chloride, balance comonomer, shall yield an initial copolymer containing (a) at least vinyl chloride, and (b) not more than 99% vinyl chloride. On this basis, satisfactory comonomers for use with vinyl chloride will be those having Q2 and e2 values, as described in J. Polymer Science 2:101, correlated as follows, assuming for vinyl chloride 'Qvinyl chloride=.03 and evlnyl chloride -3:

Instead of the single unsaturated comonomers of the types above indicated, mixtures of such comonomers may enter into the copelymers, it being understood that the total quantity thereof shall be small enough (i. e., not over 40%,based on the weight of copolymer) that the essential character of the polyvinyl chloride chain is retained- With the foregoing general discussion in mind, there are given herewith detailed examples of the practice of this invention. All parts giv n are .by weight.

EXAMPLE g A. Preparation of the linear polyesters.

grams moles Adioic acid l 2,923 20 1, 4-Butanediol or ethyl (Per Table IV) 1,000 or 1,061 (respectively) OX0 Nonyl Alcohols (Mixture of alcohols, containing about 97.5% by weight of 3,5,5-trlmethyl hexanol; produced by hydrogenation of petroleum hexene in the presence of carbon monoxide. Marketed by E. I. du Pont de Nemours and Go. as nonyl alcohols) 2,885 Toluene 433 temperature to 200 C. at which temperature the pressure was reduced to 1-.-2 mm. In these latter -..'stages of low pressure distillation, all condensate 3. Treatment with Coo Parts Linear polyester being treated (per Table IV) 100 Calcium oxide (finely powdered, reagent grade) 1-10 A series of treatments of separate portions of the linear polyesters prepared as described above was carried out, using various esters, temperatures, times of treatment, etc. for the individual runs as indicated in Table IV. In each case the selected linear polyester, with the selected proportion of calcium oxide, were stirred together in a flask and heated for the time indicated in Table IV. At the end of the heating period, the mixture was cooled, and filtered to remove the calcium oxide. In some cases of highly viscous products, the f ltration was carried out at higher temperatures, and/or with addition of solvents such as toluene.

' C; Testing I Parts Polyvinyl chloride (prepared in granular suspension in water) 100 Linear polyester under test Calcium stearate 0.5 Tricalcium phosphate 1.0 Silicate filler 1.5 Cadmium lauryl mercaptide 2.0

A series of tests was made. using various linear polyesters in formulations in accordance with the above recipe. In each case. the materials were compounded on a roll mill, and then sheeted off at a thickness of .025 inch. A strip of the sheet was then hung in an oven at 1'70 C. for two hours, removed, and subjectively rated by the operator as to extent of deterioration. The results are set out in Table IV.

Table 1 V 02.0 Treatment Ingredients of Linear ZPolyester Temperature Item Parts 030 Appearance of Sheet No.

Adlplc Acid, Dlethylene Glycol and "0x0" N onyl Alcohol Time, Minutes 35 After 2 licurs at pnlyester C.

no treatment 1 900 2 .3 4 5 6 2. 7 2. 8 2. 9 2. 10 2. 11 2. 12 2. 13 5' it 210 10 1e 2. 5 o 17 2. 5 light tan, speckletL 18 2. 5 Straw, speckled-- 19 2. 5 d 20 200 2. 5 21 2. 5 22 2. 5 23 this time. The pressure in the vessel was then reduced to 50 mm. with continual increase in From the foregoing general description and detailed specific example, it will be evident that this invention provides novel treated linear polyesters which impart excellent heat-ageing properties to vinyl chloride resins into whichthey may be incorporated. The treated polyesters have all of the excellent plasticising properties characteristic of the untreated polyesters. The process may be carried out by means of relatively simple and inexpensive equipment and with a minimum of technical supervision.

What is claimed is:

1. Process which comprises contacting. with calcium oxide, at temperatures from 150 to 250 C., and for a time of at least minutes, a, mixture of linear polyesters produced by esterifying together Moles A free alkylene dicarboxylic acid containing 4-12 carbon atoms 2 A diol selected from the group consisting of alkylene glycols and diglycols containing 2-12 carbon atoms 1110.1 A monohydric alcohol selected from the group consisting of alkanols .and a1- koxyalkanols containing from 4-12 carbon atoms 210.1

the calcium oxide being present to the extent of at least 0.5%, based on the weight of the linear polyesters.

2. Process which comprises contacting, with calcium oxide, at temperatures from 150 to 250 C., and for a time of at least 15 minutes, a mixthe calcium oxide being present to the extent of at least 2-10%. based on the weight of the linear polyesters.

3. Process which comprises contactingfl .with calcium oxide, at temperatures from 175..C. to 250 C., and for a time of at least 15 minutes, a mixture of linear polyesters produced by es'terifying together A free alkylene dicarboxylic acid containing 4-12 carbon atoms 2" A diol selected from the group consisting of alkylene glycols and diglycols containing 2-12 carbon atoms 11-01 A monohydric alcohol selected from the group consisting of alkanols and alkoxyalkanols containing 142 carbon atoms 2:0.1

Moles 8 the calcium oxide being present to the extent of at least 0.5%; based on the weight of the linear polyesters.

4. Process which comprises contacting, with calcium oxide, at temperatures from 175 to 250 C., and for a time of at least 15 minutes, a mixture of linear polyesters-produced by esterifyingtogether Y Moles Adipic acid 2 lgl-butanediol 1:0.1

The alcohols produced by hydrogenation of petroleum hexene in thepresence of carbon monoxide 2:0.1

6. The stabilized polyesters produced by the process of claim 1.

'7. The stabilized polyesters produced by the process of claim 2.

8. The stabilized polyesters produced by the process of claim 3.

9. The stabilized polyesters produced by the process of claim 4. a I

10; The stabilized-polyesters produced by the process of claim 5. 1

11. A heat-stable; plasticized composition comprising a vinyl chloride resin and the stabilized polyesters produced by the process of claim 1.

12. A heat-stable, plasticizedcomposition comprising'a vinyl chloride resin and the stabilized polyesters produced by the process of claim 2.

13. Aheat-stable, plasticized composition comprising a vinyl chloride resin and the stabilized polyesters produced by the process of claim 3.

14. A heat-stable, plasticized composition comprising a vinyl chloride resin and the stabilized polyesters produced by the process of claim 4.

15. A heat-stable, plasticized composition comprising a vinyl chloride resin and the stabilized polyesters produced by the process of claim 5.

y W. MAYO SMITH, JR.

ROBERT J. REID.

' No references cited. 

1. PROCESS WHICH COMPRISES CONTACTING, WITH CALCIUM OXIDE, AT TEMPERATURES FROM 150* TO 250* C., AND FOR A TIME OF AT LEAST 15 MINUTES, A MIXTURE OF LINEAR POLYESTERS PRODUCED BY ESTERIFYING TOGETHER 